In general, the fundamental steps of processing processes for silver halide color photographic materials include a color developing step and a silver removing step. That is, when a light-exposed silver halide color photographic material is color-developed, the silver halide is reduced by a color developing agent to form silver and at the same time the oxidized color developing agent reacts with couplers to form dye images. Thereafter, the color photographic material is subjected to a silver removing step, wherein silver formed in the previous step is oxidized by the action of an oxidizing agent (called a bleaching agent), dissolved by a complexing agent for silver ion (generally called a fixing agent), and removed from the photographic material. Thus, dye images only remain in the photographic material. Practical processing processes for color photographic materials include auxiliary steps for keeping the photographic and physical qualities of the dye images and/or improving the stability of the dye images in addition to the above-described steps of color development and silver removal. Examples include a hardening bath for preventing photosensitive emulsion layers of color photographic materials from being excessively softened during processing, a stop bath for effectively stopping the development reaction, an image stabilizing bath for stabilizing dye images, a de-filming bath for removing a backing layer from the support of a color photographic material, etc.
Also, as the above described silver removing step, there is a case of performing silver removal in a single step using a blix bath containing a bleaching agent and a fixing agent, and a case of performing silver removal in two steps using a bleach bath and a fix bath separately.
In general, as a bleaching agent for a bleaching solution, a ferricyanide, potassium bichromate, a ferric ion complex salt, a persulfate, etc., is used. Among the bleaching solutions containing these materials, a bleaching solution containing a ferricyanide has the most excellent bleaching action, but has the disadvantage that a ferricyanide ion and a ferrocyanide ion, which is a reduced form of a ferricyanide, may be discharged by being overflown during processing and being carried in washing water after bleaching, can sometimes form cyan compounds by causing photochemical oxidation, which cyan compounds have a strong toxicity and cause serious environmental pollution problems. Accordingly, the development of excellent and non-toxic bleaching agents for such a ferricyanide has been desired.
A ferric ion complex salt is sometimes used as a bleaching agent in a blix solution for color photographic papers as disclosed, for example, in German Pat. Nos. 866,605 and 966,410, and in U.K. Patent Nos. 746,567, 933,088 and 1,014,396. However, a bleach solution or a blix solution containing a ferric ion complex salt has a weak oxidizing power, and hence when the bleach or blix solution is used for photographing color photographic materials using silver iodibromide and having a high concentration of silver halide, it takes a long period of time for processing.
At any rate, a bleaching process using a metal ion such as a ferricyanide and a ferric ion complex salt is accompanied by the troublesome problem of disposing the waste solution, and hence a bleaching process avoiding use of such a metal ion, i.e., a bleaching process using a persulfate, is more desirable. However, a persulfate also has a disadvantage that the bleaching power thereof is weaker than a ferric ion complex salt, and it thus takes a very long period of time for bleaching. Accordingly, for processing color photographic materials using a large amount of silver halide and having a high sensitivity, a new technique capable of accelerating the bleaching action by a persulfate or a ferric ion complex salt has been desired.
For accelerating the bleaching action of a persulfate or a ferric ion complex salt, a process of adding an amino compound represented by formula (I) ##STR3## wherein M represents a hydrogen atom, an alkali metal atom, an alkaline earth metal atom, a quaternary ammonium group, a quaternary phosphonium group, an amidino group, or a group represented by ##STR4## R.sup.1 and R.sup.2 each represents a hydrogen atom or an aliphatic residue; and m represents an integer of 2 to 4; to the processing bath (a bleach bath, a blix bath or a pre-bath for use before the bleach or blix bath) is known, as described, for example, in U.S. Pat. Nos. 3,772,020 and 3,893,858; and Research Disclosure, RD No. 15704, May, 1977.
However, it has now been clarified to one skilled in the art that when the bleach accelerator shown by above-described formula (I) is used for continuously processing color photographic materials, the bleach accelerator is liable to cause inferior fixing.
That is, when color photographic materials are subjected to a fix treatment in the state that the bleach accelerator is contained in the silver halide emulsion layers in an amount larger than some definite amount, inferior fixing is frequently liable to occur unless the silver ion concentration and the concentrations of iodide ions and other halide ions in the fix solution, as well as other factors having adverse influences on the fixing speed are strictly regulated.
The main factors for determining the concentrations of silver ions and iodide ions remaining in silver halide emulsion layers in a fix solution are the coated amount of silver and the amount of iodine mainly contained in light-sensitive silver halides. Thus, the coating amount of silver in a color photographic material and the composition of light-sensitive silver halide are strictly regulated from the viewpoint of the fixability, which is a very troublesome problem in the production of color photographic materials.
In particular, there has been a trend recently to increase the sensitivity of photographic materials as high as possible, and hence it has now become necessary from a practical viewpoint, to use a silver halide emulsion having a high silver iodide content (higher than about 4.0.times.10.sup.-3 mole/m.sup.2).
Accordingly, it is urgent need to improve inferior fixing occurring in the case of processing a color photographic material having a high silver iodide content using a bleach accelerator represented by above-described formula (I).